Improvement in hydraulic valves



' .NrTED STATES PATENT OFFICE.

THOMAS CRITCHLOW, OF BALDWIN, PENNSYLVANIA.

IMPROVEMENT IN HYDRAULIC vALvEs.

Specification forming part of Letters Patent No. 136,489, dated March 4, 1873.

To all whom it may concern:

Be it known that I, THOMAS CRiTonLow, of Baldwin, in the county of Dauphin and in the State of Pennsylvania, have inventedv certain new and useful Improvements in Hydraulic Valves; and do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawing and to the letters of reference marked thereon making a part of this specification.

The nature of my invention consists in the construction and arrangement of a hydraulic valve, for operating machinery by hydraulic or hydrostatic powersuch as, for instance, the machinery of a Bessemer-steel plant, which performs all the heavy lifting and revolving.

In order to enable others skilled in the art to which my invention appertains to make and use the same, I will now proceed to describe its construction and operation, referring to the annexed drawing, in which- Figurel is a longitudinal vertical section of my valve, showing the same in a dormant vor inactive position; and Fig. 2, is a similar view, showing the valve in an active position.

A A represent hollow cylindrical castings, connected near their ends by pipes or passages B and C. The cylinder A has a central inlet, D, and the cylinder A a central outlet, E. Each cylinder is provided with two stuffing or packing boxes, G G, cast with the cylinder, a suitable distance above and below the openings D and E, respectively, forming in each cylinder a central chamber, H. In each of the stuffing or packing boxes G is iitted a screw or stud gland, c, to tighten the packing, or to hold an ordinary hydraulic packing, although I prefer to use the ordinary hemp packing. The extreme ends of the cylinders have detachable covers I and I', which can be removed to enable the stuffing-boxes G G to be repacked at any time. The covers I I are provided with ordinary stuffing-boxes bb, through which the valve stems or rods J J pass and work. Attached to the lower end of each stem J is a hollow perforated piston, K, having its extreme ends closed so as to be perfectly water-tight. The ends of the piston may be screwed in, or cast, or held in by the stem J passing clearthrough both ends and secured by a nut or key, or both.

Each piston K is provided with two sets of perforations, d and e, each set consisting ot' one or more rows of holes extending around the piston. 'Ihese perforations are so placed that when the pistons are-in a central position, as shown in Fig. 1, the perforations will be inclosed in the central chambers or compartments H H, and thus, by the stuffingboxes GG, closing all means of communication with the chambers H1, and H2 above and below the chambers and the passages B and G. By operating the lever L, which may be attached to the valve-stems by suitable join ts and pin, to allow for the vibration of the lever on its central pivot, the pistons K K are moved, and thereby a means of communication is opened with the chambers H and H2, and the passages B and C, as shown in Fig. 2, allowing the water to pass through the perforations el/,f and d into the chamber H of the receiving-cylinder A, and out lthrough the passage B and piperB to the machine or vessel to be operated upon, which machine, if it be double-acting, will also have areturn pipe, the water so returning finding its Way through the pipe C and passage U into the chamber H2 of the discharge-cylinder A', and then through the perforations e d in the piston of the same, and out through the outlet E.

By simply reversing the lever L the pressure is reversed, and the machine or vessel operated moved in the opposite direction.

When the pistons KK are in the central position, shown in Fig. l, all communication with the passages B and Gis entirely closed so that no pressure can escape beyond the chamber H in the receiving-cylinder A; neither can the pressure escape which' may have been previously let out into the passage- Ways, as the outlet communication is also closed; and-hence the machine or vessel operated upon will remain stationary in the position to which it had been moved.

If the valve be required to operate a plunger, crane, or press, then it would only require one pipe to lead the water to it, because on lowering the crane or press the water would return through the pipe by which it was conveyed the hollow perforated piston, being' reversed, would open a means of escupe, and at the same time shut off the water communication.

Having thus fully described my invention, what l claim als new, and desire to secure by Letters Patent, is

1. The hollow piston K, closed at both ends and provided with perforations d and e, sub# stantially as and for the purposes herein setforth.

2. The cylinders A A', connected by pipes B C, and each provided with stuirlng or packing.,1r boxes G G, to form interior compartments H, H1, und EL2 in each cylinder, substztni tially as and for the purposes herein set forth.

Witnesses:

C. L. EVERT, A. N. MARR. 

